DIY_EFI Digest Saturday, August 14 1999 Volume 04 : Number 468 In this issue: Re:Digest V4 #464 / William T Wilson comments Re: DIY_EFI Digest V4 #467 See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sat, 14 Aug 1999 16:58:37 +0800 From: Ken Tompson Subject: Re:Digest V4 #464 / William T Wilson comments Hi All, I have been following along for about a week and am finding I need to get in 15 mins earlier each day in order to have a quick sniff through the digest. The question, "Will a PC be able to run an engine using Windows operating system?" I think not. If you can get it running properly, I will take off my shoes and walk to Sydney in bare feet, a trip of about 3000 miles. Look, I am sure the engine will run, but so does a K-Jetronic or sprint car with its garden hose sprinkler system. We sample combustion pressure at rocket fast speeds using a PC. We make an encoder for 360 pulse per rev, or 720 ppr (plus tdc, or other reference), 10,000 rpm? on the 1/2 degree, no problem. With a serial cable deal? you are really flogging a dead horse, man this is one huge bottle neck. Windows for real time control? The main problem here is that there are only one million micro seconds in a second. So if we give the serial cable the flick, we need to digitize the analog data into RAM, so that the Intel can do something with it. WINDOWS HAS A HUGE PROBLEM AND THAT IS WINDOWS, but other operating systems are not a whole lot better at resolving our real time PC nightmare. Windows interrupt latencies is a big drama, the engine needs an answer sooner than the PC is prepared to give it. Data will enter the PC memory via one of the following pathways:- 1. A generated interrupt, telling the PC to stop what it is doing and go take a look at whatever. Very SLOW! 2. The software can be set up to go poll whatever you want looked at. Again the poor old Intel is dragged to it's knees. 3. Direct Memory Access. Dma is efficient at getting the data into memory, but it is still a slug, unless you can buffer your data on the hardware you are using, not going to give the Intel a real time picture, is it? The extra piece of hardware is triggering the sampling (not the Intel Pentium). A PCI add-in with a bus master controller, is a slightly different twist. So now we are not limited to ISA Dma availability, but this was not our problem. The tightest code that you will write, will be with a WATCOM C/C++ version 11 compiler. You can set up your globals to act as a server for the various events taking place. We have a virtual dyno controller set up exactly like this, so I know the PID update rate that is possible. The faster the Pentium, the greater your chances of course. We are able to sample at 1 Mega HZ and even much faster, but then the PC is merely a tool to display collected data, the add-in hardware with its on board firmware and co-processor does all the work, not the PC. I once had a little steam engine that ran. Just add water and methylated spirits and it went round and round and up and down, but that is about all it did. A bit like our 8 stroking PC controlled engine. I had planned to stand back and watch the experiment unfold. As a newby I was not sure whether I was supposed to shut up and observe, but after reading and agreeing with the comments of W. Wilson, I guessed that it would be permissible for me to put in my 20c worth? I think this is a great venue for exchange of ideas, but a lot of work for the people doing the organizing. Regards, Kevin Jaeger. email kjaeger@xxx.au PS Remember the engine is not going to want to stop for us to take it's picture. ------------------------------ Date: Sat, 14 Aug 1999 09:09:06 -0700 From: "John Kosche" Subject: Re: DIY_EFI Digest V4 #467 I've installed an '89 Ford 5.8 injected engine in a first generation Ford van. Engine runs.. I have two wires that I have received conflicting advice on. one it the VSS (vehicle speed sensor) the second is the selector position sensor.. Are they required? Any input is appreiciated, John Kosche ------------------------------ End of DIY_EFI Digest V4 #468 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".